INTERNET-DRAFT R. Shekh-Yusef Intended Status: Standards Track Avaya Expires: November 27, 2012 M. Barnes Polycom May 26, 2012 Conference Focus Indicating CCMP Support draft-yusef-dispatch-ccmp-indication-00 Abstract The Centralized Conferencing Manipulation Protocol document defines away for a client to discover a conference control server that supports CCMP. However, it does not define a way for a client involved in a conference to determine if the conference focus supports CCMP. This information would allow a CCMP-enabled client that joins a conference using SIP to also register for the XCON conference event package and take advantage of CCMP operations on the conference. This draft describes few options to address the above limitation with the pros and cons for each approach. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Shekh-Yusef & Barnes Expires November 27, 2012 [Page 1] INTERNET DRAFT Conference Focus CCMP Support May 26, 2012 Copyright and License Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. 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Shekh-Yusef & Barnes Expires November 27, 2012 [Page 2] INTERNET DRAFT Conference Focus CCMP Support May 26, 2012 Table of Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4 2 Possible Solutions . . . . . . . . . . . . . . . . . . . . . . 5 2.1 Feature Tag . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3 Conference Event Package . . . . . . . . . . . . . . . . . . 6 2.3.1 Service URI purpose . . . . . . . . . . . . . . . . . . 6 2.3.2 Conference URI purpose . . . . . . . . . . . . . . . . . 6 3 Security Considerations . . . . . . . . . . . . . . . . . . . . 7 4 Recommendation . . . . . . . . . . . . . . . . . . . . . . . . 7 5 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 6 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7 7 References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 7.1 Normative References . . . . . . . . . . . . . . . . . . . 8 7.2 Informative References . . . . . . . . . . . . . . . . . . 8 Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Shekh-Yusef & Barnes Expires November 27, 2012 [Page 3] INTERNET DRAFT Conference Focus CCMP Support May 26, 2012 1 Introduction RFC 5239 defines a framework for Centralized Conferencing, which allows participants to exchange media in a centralized unicast conference. The framework also outlines a set of conferencing protocols for building advanced conferencing applications. The Centralized Conferencing Manipulation Protocol (CCMP) allows authenticated and authorized users to create, manipulate and delete conference objects. Operations on conferences include adding and removing participants, changing their roles, as well as adding and removing media streams and associated end points. The Centralized Conferencing Manipulation Protocol (CCMP) draft defines a way for a client to determine a conference control server that supports CCMP, but it does not define a way for a client to determine if a conference focus supports CCMP. This draft describes few options to address the above limitation with the pros and cons for each approach. 1.1 Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. Shekh-Yusef & Barnes Expires November 27, 2012 [Page 4] INTERNET DRAFT Conference Focus CCMP Support May 26, 2012 2 Possible Solutions 2.1 Feature Tag This approach defines a feature parameter 'ccmp' to express that a SIP dialog belongs to a conference that supports CCMP. The use of feature parameters in Contact header fields to describe the characteristics and capabilities of a UA is described in the User Agent Capabilities document. The focus behavior regarding the handling of the 'ccmp' feature is the same as the handling of the 'isfocus' feature parameter. In session establishment, a focus MUST include the 'ccmp' feature parameter in the Contact header field unless the focus wishes to hide the fact that it is a focus. The pros of this approach is a one step discovery of the focus and its ccmp support, and the fact that it can be used in response to an OPTIONS request, and that it enables the discovery of the ccmp capability by any network element that does not need the conference event package. The cons is the definition of a new feature parameter. 2.2 OPTIONS This approach requires the client to send an OPTIONS request to the conference focus to determine if the conference supports CCMP. If the feature tag approach is used, then the 200 OK response to the OPTIONS request MUST include the ccmp feature parameter in the Contact header. Another option is to return the Call-Info header with an XCON-URI in the 200 OK . The pros of this approach is that it is consistent with SIP in terms of the mechanism by which a UA determines the capabilities of a SIP intermediary, and that it enables the discovery of the ccmp capability by any network element that does not need the conference event package. The cons is that it requires an extra step to determine that a conference focus supports CCMP. Shekh-Yusef & Barnes Expires November 27, 2012 [Page 5] INTERNET DRAFT Conference Focus CCMP Support May 26, 2012 2.3 Conference Event Package There are two options that rely on the SIP conference event package defined in RFC 4575: 2.3.1 Service URI purpose Define an additional URI 'purpose' of 'ccmp' associated with a 'service-uris' element in the SIP conferencing event package. The XCON-URI for the conference is included in the 'uri' element, per the following example: XCON:conf1@example.com ccmp 2.3.2 Conference URI purpose Define an additional URI 'purpose' of 'ccmp' associated with a 'confs-uris' element in the SIP conferencing event package. ccmp: Indicates that the conference focus represented by this URI supports ccmp, which allows a client to use the CCMP protocol to manipulate the conference. This URI MUST be an XCON-URI as defined in the xcon-data-model. XCON:conf1@example.com whatever ccmp The pro of the SIP conference event package options is the use of an existing mechanism for extending the field of the or elements. The con is the requirement that the client register for the conference event package. However, given that clients that want to take advantage of CCMP would most likely register for the conference event packages. Shekh-Yusef & Barnes Expires November 27, 2012 [Page 6] INTERNET DRAFT Conference Focus CCMP Support May 26, 2012 3 Security Considerations These proposals introduce no additional security considerations beyond those which are applicable to each of the mechanisms described herein. 4 Recommendation This document recommends two mechanisms: * Call-Info that can be used with INVITE requests and responses, and responses to OPTIONS requests. * because it is typically used for ancillary or meta-information about the conference. This recommendation allows UAs that are interested in subscribing to the conference event package to discover the CCMP capabilities without any extra steps, while it allows UAs that are not interested in subscribing to the conference event package to discover if a conference focus supports CCMP without forcing them to subscribe to the conference event package. 5 IANA Considerations 6 Acknowledgments The authors would like to thank Alan Johnston and Robert Sparks for their careful review and feedback. Special thanks to Adam Roach for his thorough review, comments, and suggestions. Shekh-Yusef & Barnes Expires November 27, 2012 [Page 7] INTERNET DRAFT Conference Focus CCMP Support May 26, 2012 7 References 7.1 Normative References [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [RFC5239] Barnes, M., Boulton, C., and O. Levin, "A Framework for Centralized Conferencing", RFC 5239, June 2008. [RFC4575] Rosenberg, J., Schulzrinne, H., and O. Levin, "A Session Initiation Protocol (SIP) Event Package for Conference State", RFC 4575, August 2006. [RFC6503] Barnes M., Boulton, C., Romano S P., and Schulzrinne H., "Centralized Conferencing Manipulation Protocol", RFC6503, March 2012. 7.2 Informative References Shekh-Yusef & Barnes Expires November 27, 2012 [Page 8] INTERNET DRAFT Conference Focus CCMP Support May 26, 2012 Author's Addresses Rifaat Shekh-Yusef Avaya 250 Sidney Street Belleville, Ontario Canada Phone: +1-613-967-5267 Email: rifatyu@avaya.com Mary Barnes Polycom TX US Email: mary.ietf.barnes@gmail.com Shekh-Yusef & Barnes Expires November 27, 2012 [Page 9]